Discharge printing



Patented Oct. 17, 1933 UNITED, STATES DISCHARGE PRINTING FrederickBaxter Downing, Carneys Point, N. 1., and Richard G. Clarkson'Wilmington, DeL, assignors to E. L du Pont de Nemonrs & Company,Wilmington, -Del., a corporation of Delav ware.

No Application December 29, 1930 Serial No. 505,464 a 19 Claims.

This invention relates to the art of textile printing and moreparticularly to the discharged dyed style of printing upon the celluloseester and ether type of artificial silk. It specifically contemplatesthe utilization of organic thiocyanates as swelling agents for celluloseacetate textile material.

There is a type of textile printing known as the discharged dyed style".In general this process comprises dyeing the fabric throughout andthereafter printing on certain portions or areas thereof what is knownas a discharge paste. This paste is a composition comprising somesubstance or substances capable of removing, destroying or permanentlydecoloring the dye already aflixed to the fabric. Upon suitableaftertreatmcnt the color is removed at the places in contact with thedischarge paste.

There is a modification of this process known as "color, dischargeprinting which is generally the same asthe process abovedescribed exceptthat the discharge paste comprises another dye so that upon discharge ofthe original dye from the dyed fabricthe second dye (that is, the

dye in the discharge paste) remains on the dis- I charged portion. Aswill be obvious the second dye is of a type which is not adverselyaffected by the color discharging materials' pre'sent in the paste.

It is known that the dyeing of cellulose acetate and the like is adifferent phenomena from the Cellulose acetate is dyed dyeing of otherfibers. by reason. of the formation of'the solid solution of thedyestuii' in the fiber. The dyeing of other fibers resultsfrom theadsorption of minute particles of the dyestufl upon the surface of thefiber (Brandenberger Textiliber 10, 215, 461:" 1929) v The ordinaryreduction discharge methods at 40 present in general use for theproduction of discharge efiects upon silk, wool and cotton mate- Y rialsare based upon the use of sodium formaldehyde-sulfoxylate as adischarging agent. These methods are ineffective when applied to thecellulose acetate type of fiber. Heretofore, in the discharging ofcellulose acetate dyeingsit has been found necessary to use adifl'erent'discharging agent or to add to the paste containing theordinary discharge agent a substancewhichwill swell the fiber and permitits penetration by the reducing or decoloring agent. The materials usedfor swelling the fiber are commonly known as swelling agents. v

As an example of the first of the two procedures noted, mention may bemade of the disclosure by of cellulose esters or ethers.

vFischesser (U. s. Patent 1,747,540: of Feb. 18,

1930) relating to neutral zinc sulfoxylate as, a

discharging agent. l s

In the second of the above procedures, the swelling agents heretoforeknown and used are such compounds as triacetin, cyclo-hexanone andethylene glycol. Recently Smith (U. S. Patent 1,651,639 of Dec. 6, 1929)has proposed ammonium sulfo-cyanide, calcium ,sulfo-cyanide and bariumsulfa-cyanide as swelling agents. With many dyes ,however, even with useof these sulfocyanides the reduction has been insuiiiciently complete tobe commercially practical. 1

This invention has as an object the provision of a method for producingclear and white discharges'upon fabrics composed wholly or in partFurther objects are the production of discharges upon fabrics ofcellulose derivatives of dyes which have not heretofore beendischargeable, the provision of new. (5 color discharge printingprocesses and effects on cellulose estersor ethers, the provision of newrelustering processes for cellulose esters or ethers, and in general anadvancement of the art. Other object will appear hereinafter,

These objects are accomplished by the present invention according towhich organic thiocyanates are incorporated in discharge printingpastes. 'The invention will be readily understood from a considerationof the following examples and description in which the parts are givenby weight.

/ j Discharge printing paste Twenty (20) partsof sodiumformaldehyde'sulfoxylate were dissolved in 55 parts of gum tragavcanthsolution containing 60 parts of gum tragacanth in'one thousand parts ofwater and when the sulfoxylate was in complete solution 25parts of aguanidine thiocyanate solution of-approximately 50% by weightstrengthwas added. Example I A fabric composedof cellulose acetate was dyed" inthe customary manner with Ionamine A powder, diazotized, developed withbeta-oxy-naph- I thoicf-acid and was afterwards printed with thedischarge printing paste described above. After the fabric hadbeenprinted it was aged for 3-5 minutes in an ordinary type of rapid-ager at100 C. It was then washed in water at 60 C. 10

for 3 minutes and dried; A pure white discharge was obtained. J a v Whenthe above procedure was repeated with the substitution of 25 parts of a50% ammonium sulfocyanide solution for the 25 parts of guaniin the art.

dine thiocyanate solution the dyestufl of the printed design was onlyslightly affected. The discharge was very incomplete.

' Example II A fabric composed of cellulose acetate was-dyed with1-methyl-4-amino-5-methoxy-benzene-azo- 4-berizamid in the customarymanner and was afterwards diazotized and coupled with betanaphthol inthe customary manner. It was then printed and afterwards treated asdescribed-in Example I. The discharge obtained by the use of guanidinethiocyanate was a clear white, whereas that obtained by the use ofammonium sulio-cyanide was of a yellowish cast.

Example 111 Material composed of cellulose acetate was dyed in thecustomary manner with Cibacete diazo black B and was afterwardsdiazotized and coupled with, beta-oxynaphthoic acid in the customarymanner. The material was then printed and afterwards treated asdescribed inExample I. A complete discharge of slightly yellowish tonewas obtained by the use of guanidine thiocyanat'e whereas the use ofammonium sulfocyanide produces no appreciable discharge effect.

I Example IV -Material composed of cellulose acetate was dyed in thecustomary manner with Celitazol AZ and was afterwards diazotized andcoupled with beta-oxynaphthoic acid in the customary man- The resultingpaste was then cooled and when cold 10 parts of Ponsol brilliant green Gpaste -(dimethoxy-diloenzanthrone) was added and uniformly mixed in bystirring.

After the fabric had been printed it was aged for 3-5 minutes in anordinary type of rapid 861' at 100C. 1 It was then washed in water at C.and dried. .A brilliant green print on a black ground was obtained.

When the above procedure wasrepeated'with,

the substitution of 10 parts of ammonium sulfocyanide forthe 10 parts ofguanidine thiocyanate,

the shade of the printed design was much duller and weaker. In thedischarge paste above described, potassium or other alkali metalformaldehyde-sulfoiwlates maybeusedifdesired. g I

The amount of guanidine thiocyanate to be added to the discharge pastefor the production -of satisfactory discharges varies so widely thatdefinite limits cannot be given. The. amount to be used depends upon thenature of the fabric,-

the size of the filaments, the nature of the dyestuffs employed-thestrengthof the dyeing and the like. No general. rule can therefore belaid down as to the concentration of the reagent to be employed. Foreach specific case this may be readily determined by experiment by oneskill Variations in the discharging cond t ons may be made if desired.

Preferably the guanidine thiocyanate is added to the variouscompositions mentioned in the form of its aqueous solution.

when guanidine thiocyanate isemployed as the swelling agent a part ofthe beneficial effects obtained are undoubtedly due to the presence ofthe guanidine radical. This is shown by the fact that discharges areproduced by the use of this reagent which are unobtainable by the use ofan equal weightof ammonium sulfocyanide. This is true in spite of thefact that a given quantity of ammonium sulfocyanide contains 50% more ofthe sulfocyanide (thiocyanate) radical than an equal amount of guanidinethiocyanate.

Guanidine thiocyanate may also be used as a printing assistant in colorprinting on acetyl cellulose and other cellulose esters and ethers. Itis, in addition, a valuable relustering agent for these materials.

Numerous advantages of the invention are outstanding. Among these may bementioned (1) The production of discharges of a character unobtainableby previously known methods. This is especially true on more diflicultlydischargeable colors such as those of the examples. 100

(2) The production of white discharges of superior stability. Thesamples of Example II were .to the specific embodiments thereof exceptas defined in the appended claims.

We claim:

1. The process which comprises printing adischarge compositioncontaining guanidine thio-, cyanate on dyed cellulose acetate materialand finishing the discharge operation by'ageing at about 100 C., washingand drying.

2. The production of discharge effects on acetyl cellulose materialswhich comprises the addition of guanidine thiocyanates to an alkalimetal formaldehyde-sulfoxylat'e discharge printing pasta. 3. Theproduction of color discharge effects on acetyl cellulose materialswhich comprises the addition of guanidine thiocyanates to an alkali 131)metal formaldehyde-sulfoiwlate discharge printing paste. V

4. A preparation for the production of discharge efiects on materialscontaining cellulose acetate comprising an alkali metal formaldehyde-135 'sulfoxylate dischargeprinting paste and a guanidine thiocyanate.-

5. A discharge composition for the class comprising cellulose estersand'ethers containing a guanidine thiocyanate and a sulfoxylate.

6. A discharge composition for the class comprising cellulose esters andethers containing an alkali metal formaldehyde sulfoxylate and aguanidine thiocyanate. v

'7. A discharge printing paste for cellulom acetate materials consistingof about 20 parts of sodium formaldehyde-sulfoxylate, about 55 parts I.of an approximately 6% gum tragacanth solution and about 25 parts of anapproximately 50% guanidine thiocyanate solution.

-8. A discharge printing paste for cellulose acetate materialscomprising sodium formaldehydesulioxylate, gum and guanidinethiocyanate.

9. The production of d'scharge eiiects on materials oi the classcomprising cellulose esters and ethers which includes treatment with aguanidine thiocyanate.

10. The production of discharge effects on materials oi the classcomprising cellulose esters and ethers which includes treatment withguanidine thiocyanate.

11. The production of discharge eflects on cellulose acetate materialswhich includes treatment with guanidine thiocyanate.

12. The process which comprises printing a discharge paste containing aguanidine thiocyanate on materials or the class comprising celluloseesters and ethers and thereaiter discharging by ageing at about 100 C.,washing and drying.

13. The process which comprises printing a discharge paste containing aguanidine thiocyanate on cellulose acetate materials and thereafterdischarging by ageing at about 100 C., washing and (1171 8 14. Theprocess which comprises printing a discharge paste containing an alkalimetal formaldehyde-sulioxylate and a guanidine thiocyanate on materialsof the class comprising cellulose esters and ethers and thereafterdischarging by ageing at about 100 C., washing and drying.

15. The process which comprises printing a discharge paste containing aguanidine-thiocyanate on materials of the class comprising celluloseesters and ethers and thereafter discharging by ageing at about 100 C.,washing and drying.

16. The process which comprises printing a discharge paste containing analkali metal formaldehyde-sulloxylate and a guanidine thiocyanate oncellulose acetate materials and thereafter discharging by ageing atabout 100 C.,' washing and drying.

1'7. A discharge composition for the class comprising cellulose estersand ethers containing a guanidine thiocyanate and an alkali metalaldehyde sulfoxylate.

l8. Dyed cellulose acetate material having imprinted thereon a dischargecomposition containing a guanidine thiocyanate and a sulfoxylate.

19. The process which comprises printing on a dyed cellulose acetatematerial a discharge composition containing an alkali metal aldehydesulioxylate and a guanidine thiocyanate and thereafter aging theimprinted material.

FREDERICK B. DOW'NING. RICHARD G. CLARKSON.

